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| Open AccessDirect imaging of magnetohydrodynamic wave mode conversion near a 3D null point on the sun
Magnetohydrodynamic (MHD) wave mode conversion can occur when an MHD wave passes through a region where the plasma properties change. Here, the authors show direct observation of mode conversion from a fast-mode to a slow mode MHD wave near a 3D null point in the solar corona, which was as predicted by theory and MHD simulations.
- Pankaj Kumar
- , Valery M. Nakariakov
- & Kyung-Suk Cho
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| Open AccessSingle drop cytometry onboard the International Space Station
Real-time lab analysis is key to support clinical research during space missions. Here, the authors show scant test samples can be measured in microgravity using a miniature cytometery-based analyzer, the rHEALTH ONE with specific spaceflight modifications.
- Daniel J. Rea
- , Rachael S. Miller
- & Eugene Y. Chan
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| Open AccessChorus wave power at the strong diffusion limit overcomes electron losses due to strong diffusion
Strong diffusion limit is the maximum rate of electron loss into the atmosphere from Earth’s radiation belts. Here, the authors show scaling up chorus wave power to the strong diffusion limit causes rapid acceleration of electrons, sufficient to outweigh the losses due to strong diffusion.
- T. A. Daggitt
- , R. B. Horne
- & J. M. Albert
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| Open AccessExperimental study on chorus emission in an artificial magnetosphere
Plasma created in laboratory are useful to understand the properties of atmospheric and space plasma. Here the authors report a laboratory plasma experiment in a dipole magnetic field to show the excitation of chirping whistler waves, i.e. chorus emission.
- Haruhiko Saitoh
- , Masaki Nishiura
- & Zensho Yoshida
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| Open AccessSearching for ultralight dark matter conversion in solar corona using Low Frequency Array data
Hypothetical dark photon (DP) dark matter (DM) and axion DM might resonantly convert into electromagnetic waves in the solar corona. Here, the authors show upper limits on the axion-photon coupling and on the kinetic mixing coupling of DPDM and photon within 30-80 MHz in the solar corona radio observations.
- Haipeng An
- , Xingyao Chen
- & Yan Luo
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| Open AccessElectron scale coherent structure as micro accelerator in the Earth’s magnetosheath
Both particle and wave energy exist in plasma and energy transfer leads to many interesting phenomena like turbulence, particle acceleration. Here the authors show electron-scale coherent structure resulting from energy transfer in magnetosheath using a model and data from Magnetospheric Multiscale Mission.
- Zi-Kang Xie
- , Qiu-Gang Zong
- & Per-Arne Lindqvist
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| Open AccessGlobal-scale magnetosphere convection driven by dayside magnetic reconnection
A fundamental feature of planetary magnetospheres is internal convection induced by surrounding solar wind. Here, authors offer insights into the interplay among solar wind, magnetosphere, and ionosphere, and evidence a dayside-driven convection pattern linked to magnetic-field-aligned currents.
- Lei Dai
- , Minghui Zhu
- & Graziella Branduardi-Raymont
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| Open AccessMagnetosheath jets at Jupiter and across the solar system
Jets have been found in Earth’s magnetosheath for two decades and, more recently, also in Mars. Yet, their universal existence in planetary magnetosheath remains an open question. Here, authors report the presence of anti-sunward and sunward jets at Jupiter and compare them to Earth and Mars.
- Yufei Zhou
- , Savvas Raptis
- & Lan Ma
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| Open AccessSpectroscopy of a mesospheric ghost reveals iron emissions
Mesospheric ghosts are rare, faint, greenish transient luminous events. Here, the authors show metallic emissions revealed by the spectrum of a mesospheric ghost.
- María Passas-Varo
- , Oscar Van der Velde
- & Joan Montanyà
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| Open AccessEnergy transfer of imbalanced Alfvénic turbulence in the heliosphere
How and via which mechanism the energy transfers between scales in imbalanced Alfvénic turbulence is an open question. Here, the authors show that the energy transfer of imbalanced Alfvénic turbulence is completed by coherent interactions between Alfvén waves and co-propagating anomalous fluctuations.
- Liping Yang
- , Jiansen He
- & Ziqi Wu
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| Open AccessA new era in solar system astronomy with JWST
The exploration of our solar system is being radically changed since the beginning of operations of the James Webb Space Telescope (JWST) in mid 2022. JWST’s extraordinary sensitivity and instrumentation allow for sensitive searches for the building blocks of life and to test for habitability, also enabling new discoveries on small bodies to giant planets across our solar system and beyond.
- G. L. Villanueva
- & S. N. Milam
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| Open AccessObservational evidence of accelerating electron holes and their effects on passing ions
Electron holes with drift speeds comparable to local ion thermal velocity are called slow electron holes. Here, the authors show slow electron holes with non-zero acceleration can cause net velocity change of ions passing through.
- Yue Dong
- , Zhigang Yuan
- & J. L. Burch
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| Open AccessThe variable source of the plasma sheet during a geomagnetic storm
How solar wind and ionosphere contribution to the plasma in the magnetosphere during the development of geomagnetic storms changes is an open question. Here, the authors show a dynamic source change during a storm from solar wind to the ionosphere as the storm develops.
- L. M. Kistler
- , K. Asamura
- & I. Shinohara
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| Open AccessDetection of magnetospheric ion drift patterns at Mars
Mars lacks a global intrinsic magnetic field. Here, the authors show wedge-like dispersion structures of Hydrogen ions exhibiting butterfly-shaped distributions, which was previously found only in intrinsic magnetospheres.
- Chi Zhang
- , Hans Nilsson
- & Stas Barabash
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| Open AccessDrifting discrete Jovian radio bursts reveal acceleration processes related to Ganymede and the main aurora
Jovian short bursts (S-bursts) are induced by the Io-Jupiter interaction. Here, the authors show a drifting radio burst detection method and report S-bursts related to Ganymede-Jupiter interaction and to Jovian aurora.
- Emilie Mauduit
- , Philippe Zarka
- & Sébastien L. G. Hess
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| Open AccessPolarisation of decayless kink oscillations of solar coronal loops
Polarization of decayless kink oscillations of solar coronal loops provide unique information about involved excitation mechanisms and energy supply, but its detection remains elusive. Here, the authors show horizontal and weakly oblique linear polarization of such oscillations, which favors the energy supply by quasi-steady flows.
- Sihui Zhong
- , Valery M. Nakariakov
- & David Berghmans
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| Open AccessDirect evidence of substorm-related impulsive injections of electrons at Mercury
BepiColombo mission had its first Mercury flyby on 1 October 2021. Here, the authors show plasma measurements taken during this flyby, which reveals that electron injections and subsequent energy-dependent drift is a universal mechanism generating aurorae in the planetary magnetospheres.
- Sae Aizawa
- , Yuki Harada
- & Go Murakami
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| Open AccessWhistler-mode chorus waves at Mars
Although whistler-mode chorus waves are common in the Earth’s and other planetary magnetospheres, the mechanism behind fast frequency chirping is debated. Here, the authors show the presence of chorus emissions at Mars, with fundamentally the same nonlinear nature as those at Earth, despite vastly different magnetic and plasma conditions.
- Shangchun Teng
- , Yifan Wu
- & Xin Tao
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| Open AccessAssessment of the technological viability of photoelectrochemical devices for oxygen and fuel production on Moon and Mars
Long-term space missions to the Moon and Mars rely on sunlight as an energy source. Here, authors assess the performance of monolithic photoelectrochemical devices for light-assisted O2 and fuel production on the Moon and Mars as potential complementary technologies to existing life support systems.
- Byron Ross
- , Sophia Haussener
- & Katharina Brinkert
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| Open AccessLightning at Jupiter pulsates with a similar rhythm as in-cloud lightning at Earth
Potential similarities between Jovian and Earth lightning are helpful to understand involved properties. Here, the authors show that the Jovian lightning initiation processes are similar to those of intracloud lightning at Earth.
- Ivana Kolmašová
- , Ondřej Santolík
- & Radek Lán
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| Open AccessSeasonal and diurnal variations of Kelvin-Helmholtz Instability at terrestrial magnetopause
Kelvin-Helmholtz Instability (KHI) has been suggested as a significant source of geomagnetic activity during northward Interplanetary Magnetic Fields (IMF). Here, the authors show seasonal and diurnal variations of KHI at Earth’s magnetopause, highlighting the importance of Sun-earth geometry for space weather.
- S. Kavosi
- , J. Raeder
- & C. J. Farrugia
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| Open AccessUltra-high-resolution observations of persistent null-point reconnection in the solar corona
Magnetic reconnection is a fundamental energy release mechanism in space and laboratory plasmas. Here, the authors show persistent magnetic null-point reconnection in the solar corona at a scale of about 390 km.
- X. Cheng
- , E. R. Priest
- & S. Parenti
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| Open AccessParticle-sounding of the spatial structure of kinetic Alfvén waves
Kinetic Alfven Waves (KAWs) are ubiquitous in space plasmas. Here, the authors show that application of particle sounding technique to Magnetospheric Multiscale Mission data enables measuring perpendicular wavelength of KAWs.
- Z.-Y. Liu
- , Q.-G. Zong
- & G. Le
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| Open AccessPlanetary defense with the Double Asteroid Redirection Test (DART) mission and prospects
NASA’s Double Asteroid Redirection Test (DART) mission intentionally impacted the asteroid Dimorphos on September 26, 2022, and this kinetic impact changed Dimorphos’ orbit around its binary companion Didymos. This first planetary defense test explored technological readiness for this method of asteroid deflection.
- Andrew S. Rivkin
- & Andrew F. Cheng
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| Open AccessDiffuse auroral precipitation driven by lower-band chorus second harmonics
Scattering by the upper- and lower-band chorus waves are the dominant cause of diffuse auroral precipitation. Here, the authors show that the lower-band chorus alone satisfies the preferred condition for the generation of second harmonics to trigger the diffuse auroral electron precipitation.
- Xiongdong Yu
- , Zhigang Yuan
- & H. O. Funsten
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| Open AccessEquilibrium selection via current sheet relaxation and guide field amplification
Magnetized plasmas display continuous spectra of current-sheet equilibria. How they select a particular equilibrium is not well understood. Now, equilibrium selection in magnetized plasmas is studied by analytical theory, particle-in-cell simulations and spacecraft observations, highlighting the role of current-sheet relaxation processes.
- Young Dae Yoon
- , Deirdre E. Wendel
- & Gunsu S. Yun
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| Open AccessBepiColombo mission confirms stagnation region of Venus and reveals its large extent
BepiColombo mission had two Venus flybys on its way to Mercury. Here, the authors show that during its second flyby of Venus BepiColombo has crossed the stagnation region, which was predicted by the models.
- M. Persson
- , S. Aizawa
- & G. Murakami
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| Open AccessMicrowave imaging of quasi-periodic pulsations at flare current sheet
Quasi-periodic pulsations (QPPs) are frequently detected in solar and stellar flares, but the underlying physical mechanisms are still to be ascertained. Here, the authors show microwave QPPs during a solar flare originating from quasi-periodic magnetic reconnection at the flare current sheet.
- Yuankun Kou
- , Xin Cheng
- & Mingde Ding
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| Open AccessInner southern magnetosphere observation of Mercury via SERENA ion sensors in BepiColombo mission
BepiColombo mission had already two flybys of Mercury, over the total of six, as planned before entering the planet’s orbit in 2025. Here, the authors show the first ion measurements of Mercury’s inner southern magnetosphere during BepiColombo mission’s first Mercury flyby.
- S. Orsini
- , A. Milillo
- & A. Vorburger
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| Open AccessDirect observations of energy transfer from resonant electrons to whistler-mode waves in magnetosheath of Earth
Excitation of whistler-mode waves by cyclotron instability is considered as the likely generation process of the waves. Here, the authors show direct observational evidence for locally ongoing secular energy transfer from the resonant electrons to the whistler-mode waves in Earth’s magnetosheath.
- N. Kitamura
- , T. Amano
- & J. L. Burch
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| Open AccessLaboratory evidence of magnetic reconnection hampered in obliquely interacting flux tubes
Magnetic reconnection acts as energy transfer process in plasma and induces processes like plasma heating, particle acceleration. Here the authors demonstrate the variation of magnetic reconnection between two flux tubes in the presence of external magnetic field.
- Simon Bolaños
- , Andrey Sladkov
- & Julien Fuchs
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| Open AccessMeasurements of metastable helium in Earth’s atmosphere by resonance lidar
Metastable helium is a promising target for remote-sensing observations of Earth’s thermosphere. This paper reports on the development of a resonance lidar capable of resolving metastable helium density profiles and presents initial results
- Bernd Kaifler
- , Christopher Geach
- & Markus Rapp
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| Open AccessSimultaneous macroscale and microscale wave–ion interaction in near-earth space plasmas
Cross-scale energy transfers in collisionless plasmas help understanding involved mechanisms. Here, the authors show simultaneous macro- and micro-scale wave-ion interactions provide an efficient mechanism for cross-scale energy transfer and plasma energization in astrophysical and space plasmas.
- Z.-Y. Liu
- , Q.-G. Zong
- & G. Le
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| Open AccessThree-dimensional network of filamentary currents and super-thermal electrons during magnetotail magnetic reconnection
Magnetotail reconnection plays an important role in explosive energy conversion. Here, the authors show direct evidence of super-thermal electrons up to 300 keV within X-line region in Earth’s magnetotail, indicating effective electron acceleration due to turbulence.
- Xinmin Li
- , Rongsheng Wang
- & Shui Wang
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| Open AccessDirect observations of anomalous resistivity and diffusion in collisionless plasma
It is suggested that waves can provide both diffusion and resistivity that can potentially support the reconnection electric field in low-density astrophysical plasmas. Here, the authors show, using direct spacecraft measurements, that the waves contribute to anomalous diffusion but do not contribute to the reconnection electric field.
- D. B. Graham
- , Yu. V. Khotyaintsev
- & K. Dokgo
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| Open AccessSuperfast precipitation of energetic electrons in the radiation belts of the Earth
Energetic electron densities in the radiation belt increases during geomagnetic storms. Here, the authors show oblique whistler mode waves enhance electron losses and create strong fluxes of about 100 keV electrons precipitating into the atmosphere, that should be considered in radiation belt models.
- Xiao-Jia Zhang
- , Anton Artemyev
- & Ayako Matsuoka
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| Open AccessTree-rings reveal two strong solar proton events in 7176 and 5259 BCE
Two extreme solar energetic particle events have been found by carbon isotopes measured in ancient tree rings in 7176 and 5259 BCE. The recorded ~2% increases of atmospheric 14 C for both events exceeds in amplitude of all previously observed events.
- Nicolas Brehm
- , Marcus Christl
- & Lukas Wacker
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| Open AccessObservational evidence of ring current in the magnetosphere of Mercury
Ring currents have been observed in the magnetospheres of Earth, Jupiter, and Saturn. Here, the authors show observational evidence of Mercury’s ring current that is bifurcated because of the dayside off-equatorial magnetic minima.
- J.-T. Zhao
- , Q.-G. Zong
- & Y. Wei
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| Open AccessFast plasmoid-mediated reconnection in a solar flare
Solar flares provide wide range of observational details about fundamental processes involved. Here, the authors show evidence for magnetic reconnection in a strong confined solar flare displaying all four reconnection flows with plasmoids in the current sheet and the separatrices.
- Xiaoli Yan
- , Zhike Xue
- & Zhong Liu
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| Open AccessDownstream high-speed plasma jet generation as a direct consequence of shock reformation
Several mechanisms exist for formation of jets observed in Earth’s magnetosheath. Here, the authors show evidence of high-speed downstream flows generated at the Earth’s bow shock as a direct consequence of shock reformation, which is different than the proposed mechanisms.
- Savvas Raptis
- , Tomas Karlsson
- & Per-Arne Lindqvist
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| Open AccessLarge scale coherent magnetohydrodynamic oscillations in a sunspot
Co-existence of several magnetohydrodynamic oscillations modes on the Sun were predicted earlier. Here, the authors show large-scale coherent oscillations in a sunspot, with a spectrum different than solar global acoustic oscillations, incorporating a superposition of many resonant wave modes.
- M. Stangalini
- , G. Verth
- & C. D. MacBride
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| Open AccessCosmogenic radionuclides reveal an extreme solar particle storm near a solar minimum 9125 years BP
Cosmogenic radionuclides from ice cores and tree rings indicate that an extreme solar proton event has hit Earth about 9200 years ago. Contrary to expectations, the event occurred during a quiet phase of the Sun within the 11 year solar cycle.
- Chiara I. Paleari
- , Florian Mekhaldi
- & Raimund Muscheler
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| Open AccessOccurrence rate of ultra-low frequency waves in the foreshock of Mercury increases with heliocentric distance
Low frequency waves are ubiquitous in space plasmas. Here, the authors show that the occurrence rate of ultra-low frequency waves associated with backstreaming ions in the Hermean foreshock increases with Mercury’s heliocentric distance.
- N. Romanelli
- & G. A. DiBraccio
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| Open AccessDirect evidence that twisted flux tube emergence creates solar active regions
Twisted flux tubes are prominent candidates for the progenitors of solar active regions. Here, the authors show a clear signature of the emergence of pre-twisted magnetic flux tubes using magnetic winding, which detects the emerging magnetic topology despite the deformation experienced by the emerging magnetic field.
- D. MacTaggart
- , C. Prior
- & S. L. Guglielmino
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Article
| Open AccessControlled beat-wave Brillouin scattering in the ionosphere
Nonlinear wave mixing has been explored in space plasma. Here the authors report beat-wave Brillouin scattering experiment at EISCAT, in which two radio waves at different transmitted frequencies are driving ion acoustic waves in the ionosphere, leading to stimulated Brillouin emissions escaping the plasma.
- B. Eliasson
- , A. Senior
- & R. Bingham
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| Open AccessMagnetopause ripples going against the flow form azimuthally stationary surface waves
The magnetopause surface waves (SW) that drive global plasma dynamics are thought, like waves on water, to travel with the driving solar wind. Here, the authors show that impulsively-excited SW, with standing structure along the geomagnetic field, are stationary by propagating against this flow.
- M. O. Archer
- , M. D. Hartinger
- & L. Rastaetter
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| Open AccessCollisionless relaxation of a disequilibrated current sheet and implications for bifurcated structures
Bifurcated current sheets are a recurring feature in magnetized space plasmas. Here the authors explain the emergence of bifurcated structures by natural redistributions of single-particle orbits during the collisionless relaxation process of a disequilibrated current sheet.
- Young Dae Yoon
- , Gunsu S. Yun
- & James L. Burch
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| Open AccessElectromagnetic power of lightning superbolts from Earth to space
Superbolts are powerful, rare lightning events. Here, the authors show simultaneous satellite and ground measurements of a superbolt, and demonstrate different properties of superbolts and lightnings.
- J.-F. Ripoll
- , T. Farges
- & S. Pédeboy
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| Open AccessLaboratory measurements of the physics of auroral electron acceleration by Alfvén waves
It was predicted that Alfvén waves can account for the acceleration of precipitating auroral electrons. Here, the authors show laboratory measurements of the resonant transfer of energy from Alfvén waves to electrons under conditions relevant to the auroral zone as a direct test.
- J. W. R. Schroeder
- , G. G. Howes
- & S. Dorfman